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If you look carefully, notice that the rack handles are missing. I’ve owned the UD503 for just under two years and after about 18 months, I thought I was imagining that the sound quality was deteriorating. Things gradually worsened to a point where it became apparent that there was a fault with the electronics. I initially thought that I had damaged the unit with a large static discharge but now doubt that this has anything to do with the fault.

After taking the UD503 apart and running a few tests, it turrns out that the volume control chips are misbehaving and the output from the NJW1195A chips are unstable. The problem is temperature related and worsens as the unit heats up. I need more time to zoom in on the exact cause.

I also spent some time studying the circuit and feel that I can improve the DAC’s noise performance with a few simple mods. Teac took some surprising shortcuts for a Reference design and I plan to follow the AKM evaluation board manual more closely than Teac did.

So, to answer your question, the SU8 sounds better in this instance but I doubt that I could tell a good UD503 apart from a SU-8.

That's interesting. So in theory I could get a balanced amplifier, connect it to the SU-8 balanced output and connect my unbalanced tube amp to RCA. With a balanced-to-unbalanced adapter on the tube amp and balanced cables on the headphones I could have the best of both worlds. Probably too much hassle and money spent for little gain, though.

I actually ordered Blue Jeans balanced (currently in use, ~$30 each), and Ghent Audio RCA (have not received yet, ~$15 each). I'd have ordered Amazon Basics or something, which Amir recommends, but the shortest length I could find was 3 ft. I ordered 1 ft cables.

As was mentioned, and as Amir measured, the SU-8 has marginally better performance via balanced. Where it might be apparent is in channel balance at low levels:

That was why I opted to go with balanced. I think I listen at pretty low levels compared to many people; my phone's SPL meter tells me my desktop setup is currently at 60 dB (40 dB during quiet passages!), and I would rarely go any louder while sitting at my desk. (It's unlikely that I would ever be able to hear ANY of this, but I'd rather just not worry about it.)

Question on the filters: personal preference aside, it looks like the "Fast minimum" or "brickwall" filters are the "best", correct? (And few people, if any, would be able to hear a difference between Apodizing and Brickwall.)

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Question on the filters: personal preference aside, it looks like the "Fast minimum" or "brickwall" filters are the "best", correct? (And few people, if any, would be able to hear a difference between Apodizing and Brickwall.)

Member

Just got the SU-8 from Shenzen and when i checked the firmware (holding down power button as i plug in the power cable), it shows ver 1.6. Any idea on what has been changed from the well known and Amir-tested ver 1.3?

Member

Just got the SU-8 from Shenzen and when i checked the firmware (holding down power button as i plug in the power cable), it shows ver 1.6. Any idea on what has been changed from the well known and Amir-tested ver 1.3?

Member

Based on the previous posts, it looks like you have a lot of nice options for balanced cables. I would also go with amazon basics rca for now and get either blue jeans or ghent audio for balanced if you decide to stay with that cabling vs going balanced for custom length purposes. I did not know that there were so many balanced options, honestly.

Addicted to Fun and Learning

Just got the SU-8 from Shenzen and when i checked the firmware (holding down power button as i plug in the power cable), it shows ver 1.6. Any idea on what has been changed from the well known and Amir-tested ver 1.3?

Member

Just got my SU-8 from Massdrop. After having a defective Topping D50, I'm happy to announce this guy works perfectly!

I'm using it as a USB DAC for my Nvidia Shield as pictured. Does anyone know how allow apps to directly control the USB DAC? I can only set the DAC to 192kHz (High quality Stereo) or 44.1kHz (Stereo) and it doesn't appear that any apps (Plex, MX Player, etc) have the ability to set the sampling rate supplied to the DAC.